Digestion & Absorption Flashcards

1
Q

3 conditions of the gastric stomach environment that enable chemical and physical digestion are

A

• Acidic/low pH
• Enzymes secreted for protein digestion
•churning to mix contents

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2
Q

State the 2 main roles of bile in digestiom

A

• To neutralise stomach acid (by being alkaline)
• To emulsify fats

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3
Q

Where does lipase action take
Place

A

•Lumen of the small intestine

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4
Q

Explain emulsify

A

• Breaking fat droplets down into smaller droplets
*increases SA

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5
Q

How are villi adapted

A
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6
Q

What process do fatty acids and glycerol enter the epithelial cell by

A

•Simple diffusiom

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7
Q

Explain the advantages of lipid droplet and micelle formation

A

Droplets increase surface areas (for lipase / enzyme action);
(So) faster hydrolysis / digestion (of triglycerides / lipids);
Micelles carry fatty acids and glycerol / monoglycerides to / through membrane / to (intestinal epithelial) cell;

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8
Q

Increase in toxic lipid content in blood

A

Increases the risk of atheroma
Which leads to blockage in coronary arteries, increasing the risk of blood clots in the coronary arteries

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9
Q

Describe how proteins are digested in the human gut.

A
  1. Hydrolysis of peptide bonds;
  2. Endopeptidases break polypeptides into smaller peptide chains;
  3. Exopeptidases remove terminal amino acids;
  4. Dipeptidases hydrolyse / break down dipeptides into amino acids;
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10
Q

Why can only monomers be transported across the epithelial cell membrane

A

Because they are small enough and complementary to the binding sites of specific carrier proteins that move specifically complementary monomers across the epithelial cell membrane

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11
Q

Describe how glucose is absorbed from the ilium into the blood

A

Na* are actively transported out of the epithelial cell into the blood (by sodium potassium pump)
Creates a conc gradient of Na+ between the lumen of the ilium and the epithelial cell
Co transporter proteins have 2 binding sites which are complementary to both Na* and glucose. Only when both molecules bind will they be moved across the membrane
Na+ and glucose enter by facilitated diffusion using complementary Co transporter proteins
Na* diffuse into cell down conc gradient
Glucose moves into cell against conc gradient
Glucose Moves into blood vja facilitated diffusion
*ATP NOT REQUIRES WEN MOVING AGAINST CONC GRADIENT

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12
Q

Where does lipid digestion take place

A

Lumen of the ileum

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13
Q

Endopeptidases

A

Hydrolyse internal peptide bonds
Producing more ends which increases the SA
Faster hydrolysis

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14
Q

Test for starch

A

Add potassium iodide solution
Blue black colour indicates starch

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15
Q

Bile salts

A

Theyre mixed with lipid droplets to form smaller droplets (emulsified)
Which increases SA for faster hydrolysis by lipase
Bile salts glycerol and fatty acids also form micelles

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16
Q

Golgi apparatus in lipid digestion and absorption

A

Modifies triglycerides
Combines triglycerides with proteins (lipoproteins)
Forms vesicles

17
Q

What enzymes does pancreas include

A

Pancreatic amylase lipase exopeptidases

18
Q

What enzymes does the ileum contain

A

Membrane bound dipeptidases and disaccharides

19
Q

What enzymes does stomach contain

A

Endopeptidases (pepsin) + exopeptidases

20
Q

Describe and explain 2 features you would expect to find in a cell specialised for absorption

A

Folded membrane/microvilli so larger SA

Large number of carrier proteins for AT

Large number of mitochondria to release energy for AT

Membrane bound enzymes maintain conc gradienr

21
Q

Golgi apparatus in digestion

A

Modifies triglycerides
Combines with proteins then releases -exocytosis
Forms vesicles

22
Q

Describe processes involved in absorption and transport of lipid molecukes

A

Micelles contain bile salts+fatty acids+monogycerides

Micelles make fatty acids soluble in water

Fatty acids absorbed by diffusion

Triglycerides reformed in cells (Golgi apparatus)

Exocytosis

23
Q

Wat does lipase hydrolyse glycerol into

A

Fatty acids+monoglycerides